1. Field of the Invention
This invention relates to improvements in ink jet recording heads. More particularly, the present invention provides an ink jet recording head capable of handling higher resolutions by providing a manufacturing method involving no deterioration in production yield even when using pressure chamber plates that are thinner than conventionally.
2. Description of the Related Art
Ink jet recording heads according to the prior art comprise a pressure chamber plate, a nozzle plate bonded to one side of the pressure chamber plate, and a vibrating plate provided on the other side of the pressure chamber plate.
The pressure chamber plate is configured by forming multiple ink-holding pressure chambers on a silicon wafer, and bonding thereto a nozzle plate having nozzle holes arranged thereon corresponding to the pressure chambers (cavities). On the side of the vibrating plate opposite the pressure chambers are formed piezoelectric elements. Given this configuration, when the pressure chambers are filled with ink and a voltage is applied to the piezoelectric elements, changes are produced in the volume of the piezoelectric material, and hence changes are produced in the volumes of the pressure chambers. These changes in pressure cause ink to be discharged from the nozzle holes.
In the prior art, the thickness of the silicon wafer and the height of the pressure chambers are made roughly the same.
Demand has grown in recent years, however, for higher resolution in ink jet recording heads. In order to enhance the resolution of the ink jet recording head, it is necessary to reduce both the width and height of the pressure chambers and the width of the partitioning side walls between the pressure chambers.
However, the thickness of the silicon wafers that can be used currently is on the order of 200xcexc, which poses a limit on the height of the side walls partitioning the pressure chambers. When the thickness of the silicon wafer is made thinner than this, the mechanical strength of the silicon wafer cannot be preserved, leading to damage to the silicon wafer during the process of forming the pressure chambers and making handling otherwise problematic.
One conceivable solution is to form thinner pressure chamber plates separately from the piezoelectric elements, use a different base plate for forming the piezoelectric elements, and finally bond the pressure chamber plate and the piezoelectric elements together. When this is done, it is no longer necessary to send the pressure chamber plate through multiple process steps in order to form the piezoelectric elements, and the drawbacks of employing a thin pressure chamber plate can be eliminated.
However, because the height of the piezoelectric elements is no more than a few xcexc, it is very difficult to peel the piezoelectric elements away from the base plate after they are formed without affecting them.
In view of the problems noted in the foregoing, a first object of the present invention is to provide an ink jet recording head capable of handling higher resolution by employing a pressure chamber plate of thin thickness.
A second object of the present invention is to provide a manufacturing method for ink jet recording heads wherewith, by forming a pressure chamber plate of thin thickness in a separate process from the piezoelectric elements, production yield is enhanced and costs are reduced.
A third object of the present invention is to provide a manufacturing method for ink jet recording heads wherewith, by unproblematically peeling away, from the base plate, the piezoelectric elements formed in a separate process from the pressure chamber plate, whereby production yield is enhanced and costs are reduced.
An invention for achieving the first object noted above is an ink jet recording head configured so that ink can be discharged by applying a voltage to piezoelectric elements, comprising: (a) a pressure chamber plate whereon are formed pressure chambers having nozzles that can discharge ink, such that the nozzles open in the same direction, (b) a common electrode film formed so as to seal the pressure chambers on a surface of the pressure chamber plate different from the surface whereon the nozzles are provided, (c) piezoelectric elements comprising piezoelectric thin films and upper electrodes, formed severally in positions corresponding to the pressure chambers on the common electrode film, and (d) a reservoir piece provided with a lid-shaped structure that accommodates in the interior thereof one or more piezoelectric elements, the interior whereof forms a reservoir.
The ink jet recording head according to the present invention is configured such that the nozzles and the pressure chambers are formed integrally by the same component or components.
An invention for achieving the second and third objects noted above is a manufacturing method for an ink jet recording head configured such that ink can be discharged from nozzles provided in pressure chambers by applying a voltage to piezoelectric elements and changing the volume thereof, comprising: (a) a peeling layer formation process for forming a peeling layer for producing peeling by the irradiation of light onto a base plate exhibiting light-transmissivity, (b) a common electrode layer formation process for forming a common electrode film on the peeling film, (c) a piezoelectric element formation process for forming a plurality of piezoelectric elements on the common electrode film, (d) a reservoir formation process for forming a reservoir piece provided with a lid-shaped structure that accommodates in the interior thereof one or more piezoelectric elements, the interior whereof forms a reservoir, (e) a peeling process for causing peeling in the peeling layer by irradiating the peeling layer from the base plate side with prescribed light, thereby peeling away the base plate, and (f) a bonding process for bonding the pressure chamber plate provided with the plurality of pressure chambers onto the common electrode film from which the base plate has been peeled, so as to seal the pressure chambers.
An invention for achieving the second and third objects noted above is a manufacturing method for an ink jet recording head configured such that ink can be discharged from nozzles provided in pressure chambers by applying a voltage to piezoelectric elements and changing the volume thereof, comprising: (a) a peeling layer formation process for forming a peeling layer for producing peeling by the irradiation of light onto a first base plate exhibiting light-transmissivity, (b) a common electrode layer formation process for forming a common electrode film on the peeling film, (c) a piezoelectric element formation process for forming a plurality of piezoelectric elements on the common electrode film, (d) an adhesive joining process for adhesively joining a second base plate, through an adhesive layer, to the surface whereon the piezoelectric elements are formed, (e) a first peeling process for causing peeling in the peeling layer by irradiating the peeling layer from the first base plate side with prescribed light, thereby peeling away the first base plate, (f) a bonding process for bonding the pressure chamber plate provided with the plurality of pressure chambers onto the common electrode film from which the first base plate has been peeled, so as to seal the pressure chambers, and (g) a second peeling process for peeling away a second base plate.
The present invention also comprises an intermediate layer formation process for forming an intermediate layer between the peeling layer and the common electrode film.
Based on the present invention, the piezoelectric element formation process comprises a process for laminating a piezoelectric layer onto the common electrode film, a process for forming an upper electrode film on the piezoelectric layer, and a process for forming piezoelectric elements by etching the laminated piezoelectric layer and upper electrode layer.
Based on the present invention, the peeling layer may be formed using a material that is either amorphous silicon, an oxide ceramic, a nitride ceramic, an organic polymer, or a metal.
Based on the present invention, the pressure chamber plate is fabricated by a process for forming a resin layer in a die, a process for peeling the resin layer away from the die, and a process for making holes in the resin layer corresponding to the nozzles.
Based on the present invention, the second peeling process causes peeling to occur at the interfaces between the adhesive layer, and the piezoelectric elements and the common electrode film.
Based on the present invention, the second peeling process causes peeling to occur in the adhesive layer.
Based on the present invention, the adhesive layer is configured so that it contains a substance that can be hardened by the application of energy.
Based on the present invention, the adhesive layer is made up of a thermoplastic resin.
Based on the present invention, an intermediate layer formation process is also comprised for forming an intermediate layer between the adhesive layer and the second base plate.
Based on the present invention, the intermediate layer is configured so as to contain one or more metals selected from among Ni, Cr, Ti, Al, Cu, Ag, Au, and Pt, and causes peeling to occur at the interface between the intermediate layer and the adhesive layer.
Based on the present invention, the intermediate layer is made either of porous silicon or an anodic oxide film, and, during the second peeling process, causes peeling to occur either in that intermediate layer or between that intermediate layer and the second base plate.
Based on the present invention, the intermediate layer is formed using a material that is either amorphous silicon, an oxide ceramic, a nitride ceramic, an organic polymer, or a metal, and, in the second peeling process, causes peeling to occur in the intermediate layer by irradiating that intermediate layer, from the second base plate side, with prescribed light.